The invention relates to the technical field of OLED displays, and in particular to a preparation method for a printing OLED display.
An organic light-emitting diode (OLED) is an important display technologies, and for a traditional OLED display prepared with a full evaporation process, a fine metal mask (FMM) for evaporation must be used to define RGB sub-pixels, resulting in complex process and high cost. At present, the industry has been actively adopting a printing process (mainly inkjet printing) to prepare the RGB sub-pixels, which is simple in process and low in cost, and the OLED display prepared with this printing-containing process is called as a “printing OLED display”. The printing OLED display is substantially characterized by preparing a luminescent layer with the printing process (mainly inkjet printing), and other organic functional layers thereon or thereunder can be prepared either with the printing process (inkjet printing, screen printing, spin coating, spray coating, blade coating, imprinting etc.) or an evaporating process.
The overall structure of pixels of a single printing OLED display is shown in FIG. 1, and in general, the current printing OLED technology is to prepare respective layers {circle around (2)}, {circle around (3)}, {circle around (4)} and {circle around (5)} in sequence on an anodic substrate {circle around (1)} and complete it with encapsulation finally. The core of the difficult therein is to form a RGB luminescent layer {circle around (3)} through the inkjet printing, where the solution drops for the inkjet printing are likely to spill and mix mutually, thereby failing the defining of RGB sub-pixels. The reason is that in the prior art, a pixel defining layer on the anodic substrate is restricted by the process during the inkjet printing of the RGB luminescent layer, and the pixel defining layer can hardly meet the requirements of the inkjet printing in the following two aspects: (1) its thickness is difficult to increase to lead to the limited volume of the sub-pixel pits for accommodating the solution drops; and (2) it is difficult to reduce the affinity of its material (polyimide) to the solution drops, resulting in easy diffusion of the solution drops.